hlp 2000 10 prsnttn cifnaturalchallengesinriparianzonesofabsfoothills
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https://foothillsri.ca/sites/default/files/null/HLP_2000_10_Prsnttn_CIFNaturalChallengesinRiparianZonesofABsFoothills.pdfTRANSCRIPT
Natural Challenges in Riparian
Zones of Alberta’s Foothills
Kris McCleary and Dave Andison
Bandaloop Landscape-Ecosystem
Services
Practical Question:
How could riparian zones be managed
to better approximate natural
patterns?
Scientific Questions:
1. Do fires differentially affect riparian
zones?
2. Do riparian zones pose unique
emulation issues?
Transect 6, Little Berland River
Tree DBH Along Transect
0
5
10
15
20
25
30
35
40
45
50
0 150 300 450 600 750 900
Distance Along Transect (m)
Tre
e D
BH
(cm
)
Upland
Riparian
ÿ
10% of samples showed obvious
evidence that the last fire stopped
at the riparian zone.
Transect 6, Little Berland River
Tree Age Along Transect
0
50
100
150
200
250
300
0 200 400 600 800 1000
Distance Along Transect (m)
Tree
Age
Upland Riparian Transition
Transect 6, Little Berland River
Tree Age Along Transect
0
50
100
150
200
250
300
0 200 400 600 800 1000
Distance Along Transect (m)
Tre
e A
ge
Upland Riparian Transition
Transect 1, Emerson Creek
Tree Age Along Transect
0
20
40
60
80
100
120
140
160
0 100 200 300 400 500
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
Transect 23, Tributary of Embarras River
Tree Age Along Transect
0
20
40
60
80
100
120
0 50 100 150 200 250 300
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
16% of samples had higher than normal
veteran density in riparian zones.
Riparian zones with veterans tended to be:
- Spruce-dominated
- Across lower-order streams.
- Within very steep profiles, with
wide riparian zones.
Transect 20, Antler Creek
Tree Age Along Transect
0
50
100
150
200
250
0 50 100 150 200 250
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
27% of samples had higher than normal
levels of ingress within riparian zones.
Riparian zones with ingress tended to be:
- Pine-dominated.
- Evenly distributed across all stream
orders, all riparian zone widths.
- Evenly distributed across terrain
types.
Transect 31, Tributary of Lovett River
Tree Age Along Transect
0
20
40
60
80
100
120
0 100 200 300
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
Transect 19, Tributary to Gregg River
Tree Age Along Transect
0
20
40
60
80
100
120
140
160
180
0 50 100 150 200 250 300
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
Transect 3, Tributary of Beaver Creek
Tree Age Along Transect
0
20
40
60
80
100
120
0 100 200 300 400 500 600
Distance Along Transect (m)
Tre
e A
ge
Upland
Riparian
Transition
Scientific Question #1: Do fires differentially affect
riparian zones?
Not often. There is good evidence to suggest that
the presence of fire in riparian zones is almost as
widespread as on the upland portion of the
landscape.
This is consistent with the a landscape-level
analysis which demonstrates the larger-scale
problems of saving all riparian zones:
- linear old growth zones with no interior
- potential fire, disease, insect magnets
- fragmentation
Linear, Permanent Riparian Zones:
= No interior old forest
= Pre-determined patch sizes, shapes
= Natural disturbance problems
= Riparian zone ingress
= Concentrates old growth “types”
“Natural” Riparian Zones:
= Selective fire “skips”
= Maintains unique vegetation structures
= Dynamic old forest patches
= Dynamic patch sizes and shapes
No Restrictions - Run #1
Summary of
Disturbance
700 ha Forest
187 ha Non-F.
5.9 km. Ripar.
113 m/ha Edge
No Restrictions - Run #4
Summary of
Disturbance
700 ha Forest
108 ha Non-F.
4.1 km. Ripar.
111 m/ha Edge
No Creek Crossing - Run #2
Summary of
Disturbance
700 ha Forest
74 ha Non-F.
0 km. Ripar.
71 m/ha Edge
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10 12 14 16 18
10-year Time-steps
Proportion
of "Old"
Spruce
LFS Two-pass
Weldwood One-pass
NRV
Why?
….. riparian protection.
The proportion of “old” spruce-dominated stands will begin
to move well beyond NRV under current guidelines.
HOWEVER:
Scientific Question #2: Do riparian zones
pose unique emulation issues?
Yes. The NRV model tells us that there is no
natural equivalent to machinery PSI, skid
trails, and removing / redistributing biomass.
Pros
- Veteran control
- Ingress control
- Lower natural
disturbance hazard?
- No fragmentation
- Better landscape
distribution of old-
growth
Cons
- Compaction
- Erosion
- Overland flow
- Stream sedimentation,
temperature…?
Disturbing Riparian Zones:
The Dilemma
Seek alternatives
- winter cut
- technological innovation
- burn
- experiment / adapt / push the limits
Leave the door open – things will surely change.
What To Do?
Admit that we don’t have all of the answers yet.
Summarize what we know about the science.
- pros and cons, recognize limits of NRV
What other factors come into play?
- aesthetics
- cultural / social values
- economics
- logging risk
Tackle the key questions that remain
- risk assessment
- stream / aquatic dynamics
What To Do?